1. Field of the Invention
The present invention relates to fluid handling. More particularly, it relates to valves with explosive actuation and with fluid control by a destructible or deformable element which retains pressure.
2. Description of the Prior Art
Certain devices for a one-shot function, such as missile fin extension or automobile air bag inflation, use a source of stored, cold gas, typically at 4000 to 5000 psi. The device is pressurized from the source through a valve which is actuated at an appropriate time after a storage period which is, typically, long and indefinite so that the valve must have substantially no leakage before actuation in order that sufficient pressure remains in the source at such time. When the valve is actuated, typically by a pyrotechnic squib, leakage from the valve must be minimal so that the device remains pressurized during its operation, and the valve must remain in its actuated configuration despite large acceleration forces often associated with such one-shot functions.
Prior art valves using O-rings are not suited for such a function since they leak excessively. Certain other prior art valves of normally open construction achieve "zero-leakage" prior to actuation by using a tube extending through the valve to contain the pressurized gas, the tube being severed to close the valve on actuation thereof. After severing the tube, one portion thereof may be pinched off to prevent leakage from the one portion. Alternatively, leakage from both portions may be prevented by wedging the severing element therebetween. Similarly, certain prior art, zero-leakage, normally-closed valves retain pressurized gas by a closed tube end which is severed to open the valve. These prior art zero-leakage valves thus effectively eliminate leakage before they are actuated. However, they are they are deficient in one or more ways, as by excessive leakage after actuation, by not being positively retained in their actuated configuration, or by being inconvenient and expensive to reuse. A particular deficiency is that a single such prior art zero-leakage valve is not adapted to three-way operation. This last deficiency may be avoided by the use of several valves; however, the additional bulk, weight, and expense of several valves is highly disadvantageous in many applications of one-shot valves for high pressure, zero-leakage operation.